This invention relates generally to land mobile radios, and more particularly, to a land mobile radio providing communication of land mobile radio content using a land mobile radio network or a cellular data network.
Land mobile radios (LMRs) may be used to provide communication between different mobile units. Land mobile radio band communication, for example, public safety radio communication (e.g., police, fire department, etc.) is generally available within the VHF, UHF, 700 MHz and 800 MHz frequency bands. Part of each of these frequency bands is allocated by the Federal Communications Commission (FCC) for public safety communication services and are also referred to as Public Safety Frequency Bands. These communications also may be provided using private land mobile radio services (PLMRS).
Cellular networks also provide communication between different mobile users, for example, cellular telephones. These cellular networks, as well as LMR networks, continue to be enhanced and allow for improved operation and communication. For example, cellular networks now provide Push-to-talk (PTT) services that allow direct connect capabilities. Thus, a cellular phone user may request a direct connect communication link with another cellular phone user in a two way radio or “walkie talkie” type communication. As another example, cellular networks provide high-speed data services, such as, for example, General Packet Radio Service (GPRS), Enhanced Data Rates for GSM Evolution (EDGE), Evolution Data Optimized (EV-DO) and Universal Mobile Telephone Service (UMTS).
Known systems providing enhanced services or features, such as enhanced calling or voice features, which may be used, for example, for mission critical wireless applications, such as public safety applications, use commercial cellular services, such as PTT services, to augment and or replace traditional LMR systems. These known systems are provided using specialized gateway equipment that enable certain interoperability capabilities between an LMR system and a cellular network with, for example, PTT capabilities. The interoperability is provided by translating and/or transforming the data or voice communications to be communicated between the networks, for example, from an LMR network to a cellular network.
In the LMR area, new technologies are also being provided, including the use of digital communication instead of analog communication. Additionally, LMR systems are now using packet switching instead of circuit switching, for example, using Internet Protocol (IP) and Voice Over IP (VoIP) to enable construction of highly scalable and cost effective LMR networks.
However, these improvements also result in need to support migration to new technologies. Further, interoperability between systems deployed either by different LMR owners/operators or between different cellular carriers, particularly when different technologies are used in different systems, is increasingly important. It is known to utilize multimode terminal devices to facilitate both migration and interoperability. In LMR, these devices are often referred to as multimode radios, and in the cellular area these devices are often referred to as multimode phones.
Multimode terminal devices enable inter-system roaming, and specifically, roaming from one network and/or technology to another, without user intervention. These terminal devices change mode as a user roams between different systems provided using different technologies. Further, components for operation in multiple protocols and frequency bands may be integrated into a single terminal device. For example, in the cellular area, multimode phones can roam between TDMA and CDMA networks. In the LMR are, radios can roam between an analog trunked system and a digital trunked system.
Multimode operation is provided by the interconnection of corresponding network infrastructures. Thus, to provide transparency to a user, gateway equipment may be used to connect the various systems or networks. Known devices for communicating between different types of networks or systems use different communication components (e.g., hardware and software) each configured specifically to communicate with a particular network or system. For each system or network, the functions and operations for that system or network are implemented using the capabilities and protocols specific to that system or network. However, these systems are limited in the set of overall functions that are available because the functions and user interface available to a user depend on the system into which the terminal device has roamed.
Further, the functions of one system may differ significantly from the functions available on another system. Additionally, because of these protocol incompatibilities certain end-to-end services cannot be provided, for example, end-to-end encryption. For voice communications, the use of a gateway to interconnect systems can introduce degradation in voice quality as a result of the voice data being converted from one format to another.
Thus, these systems not only may operate at non-satisfactory quality levels, but may require additional controls and equipment to implement the interconnectivity, thereby adding complexity and cost to the overall systems.